Rustdoc uses CommonMark

for support by default

for support via a flag

Rustdoc lets you write documentation comments in Markdown. At Rust 1.0, wewere using the hoedown markdown implementation, written in C. Markdown ismore of a family of implementations of an idea, and so hoedown had its owndialect, like many parsers. The CommonMark projecthas attempted to define a more strict version of Markdown, and so now, Rustdocuses it by default.

As of Rust 1.23, we still defaulted to hoedown, but you could enableCommonmark via a flag, —enable-commonmark. Today, we only supportCommonMark.